Surface marking signal



Jan. 11, 1944. HOLT SURFACE MARKING SIGNAL Filed Nov. 20, 1942I-NVIIINTOR la P- BY Patented Jan. 11, 1944 UNITE STATES PATE SURFACEMARKING SIGNAL Pliny G. Holt, United States Navy Application November20, 1942, Serial No. 466,302 3 Claims. (01. 35-25) (Granted under theact or March amended April 30, 1928; 370 0.

markings may be used for making drift measure-- ments of the aircraft bya relative bearing method.

A further object of this invention is to provide visible targets to beused for bombing practice.

A further' object of this invention is to mark the location of apreviously seen object or occurred event.

The invention consists of a powder contained in a streamlined shell. Theshell is such that on striking water or other surface below theaircraft, it will break and release the powder. The container is eithermade of such a material as to be porous to air but not to the powdertherein contained, or is provided with a suitable vent; this is toprevent exploding at high altitudes.

The powder is of a composition which will spread into a singlehomogeneous visible spot when it is released on the surface. The powdermay be metallic or non-metallic in composition.

As examples, suitable materials are pale gold bronze powder and sodiumfiuorescein salt.

One form of this invention now successfully in use, is shown by way ofexample, in the accompanying drawing, in which,

Fig. 1 shows the side view of the signal shell.

Fig. 2 is a rear view thereof, and

Figs. 3 and 4 are sections taken along the lines 3-3 and 4-4,respectively, of Fig. l.

The shell I may be made of molded paper pulp approximately thick,chemically treated for water proofing and rigidity. Any other suitablematerial may be used in place of paper pulp, but should preferably besuch as will make the shell waterproof for at least three hours whenimmersed in water.

If the shell illustrated is made long.

about 2 lbs. of pale gold bronze powder 3 (floating) may be packed undervibration of .03 inch and securely sealed therein. The total weight inthis case should not exceed 3 lbs. complete. The outside finish shouldbe smooth. It is to be understood that the specific configuration of theshell and fins 2 is optional, the form shown in the drawing being merelyillustrative of one specific design.

Other 3,1883, as G. 757) The shell should be porous to the passage ofair but not to the passage of the powder 3, to prevent exploding whensubjected to the pressure at an altitude of 30,000 ft. at a maximum rateof change of 5,000 ft. per minute.

The material used should be such that the shell shall break on strikingthe water when dropped from a height of ft. above the water. It should,however, be strong enough to withstand breakage in ordinary handling.

Chemical Maximum Minimum Per cent Per cent Physical Maximum Per centTotal residue retained on N o. mesh 0 Total residue retained on No. 325mesh 3o Apparent density-22.5 grams per cubic inchmax.

The design should be such as to bring the center of gravity of thecompleted signal well forward in the nose of the shell.

It is to be understood that many changes in form, size and materials maybe made within the scope of the present invention which is defined inthe claims below.

This invention may be used by or for the Government of the United Statesof America for governmental purposes without the payment to me of anyroyalties thereon or therefor.

I claim:

1. A dummy bomb containing powder for marking purposes and adapted toburst upon impact comprising a casing of frangible material porous tothe passage of air but impervious to the passage of said powder wherebysaid casing will not be deformed or fractured due to changes in pressuresuch as will obtain in an aircraft as a result of sudden changes inaltitude.

2. The combination of claim 1 wherein said casing is molded from paperpulp.

3. The combination of claim 1 wherein said powder is pale gold bronze.

. PLINY G. HOLT.

